Baron Petre (/ˈpiːtə/), of Writtle, in the County of Essex, is a title in the Peerage of England.

Sir William acquired Ingatestone Hall and the surrounding manor from Henry for the full market value after it had been surrendered to the King by Barking Abbey during the Suppression of the Monasteries.

On her uncle's death in 1777 Anne became co-heiress to the baronies of Howard, Furnivall, Strange of Blackmere, Talbot, Braose of Gower, Dacre of Gillesland, Greystock, Ferrers of Wemme, Giffard of Brimsfield and Verdon.

James made him Clerk of the Closet and asked the Pope to make him a bishop and later a Cardinal but was refused both requests.

The feudal Lordship of Writtle had for centuries been the possession of the de Brus family and early chroniclers give the manor there as the birthplace of Robert the Bruce.

The family-owned Thorndon Hall, near Brentwood, is set in an extensive deer park.